Facile fabrication of COF-LZU1/PES composite membrane via interfacial polymerization on microfiltration substrate for dye/salt separation

Covalent organic frameworks (COFs) have attracted great interest as advanced membrane materials due to their uniform channel structure and high porosity. In this work, COF-LZU1/PES composite membranes were prepared via interfacial polymerization (IP) process, and the thin and defectless COFs active layers were successfully grown on poly (ether sulfone) (PES) microfiltration substrates with 1,3,5-triformylbenzene (TFB) and p-phenylenediamine (PDA) as precursors. The prepared COF-LZU1/PES composite membranes exhibit a high rejection rate (>99.0%) for the dyes with molecular size above 1.5 nm and nonselective permeation for inorganic salts (<12.0%). At the same time, a water permeance above 80.0 L m-2 h-1·bar-1 is achieved, which is much higher than many other membranes with similar rejections. Long-term filtration demonstrates that COF-LZU1/PES membranes have good water stability. The excellent water permeance, high dyes separation performance and great stability endow COF-LZU1/PES membranes the performance of removing dyes from saline wastewater.